The present invention relates to wet shaving systems of the blade type and more particularly to a shaving system having a movable blade positioned within a shaving cartridge or the like.
During the shaving process, shavers have long sought a wet shaving system which provides a smooth and comfortable shave without having annoying cuts and abrasions caused by the blade being at the wrong exposure and shave angle in response to shaving forces. For example, various approaches have been used to enable the shaving blade to move relative to the shaving cartridge or razor body in response to shaving forces encountered during the shaving process in an effort to present the correct blade exposure and shave angle.
One approach disclosed in prior art patents illustrates a blade cartridge comprised of two blades separated by a spacer with the blades and the spacer attached to a cap to form a unitary assembly. The blade assembly may be movable to various blade exposure and shave angles within various degrees of control and direction in response to forces encountered during shaving. For example, Ciaffone et al., U.S. Pat. No. 4,461,079, discloses a razor cartridge comprising a cartridge body 10 which includes a guard bar 12 (FIGS. 1-5). The guard bar 12 defines a leading skin-engaging surface fixed to the cartridge body. A rear beam 17 spans end walls 14 and 16 of the cartridge body 10 and a medial support member 13 to join the front of the cartridge 12 to the end thereof. A plurality of generally flat coplanar segments 18,19,21,22, each having an opening 23, are hinged to the rear beam 17 by mating webs 24,26,27,28 (col. 2, lines 50-52). Collectively, the segments 18,19,21,22 define a blade seat which is operable to pivot about the beam 17, thereby changing the attitude of blade edge relative to guard bar 12 (col. 2, lines 53-57). A cap 33 is apparently placed above an assembly of two skin-engaging blades 34,36, straddling a spacer 37 (FIG. 3). The two blades and the spacer are secured to one coplanar segment 21 of the blade support or blade seat by a conventional rivet 38 to form a rigid unit. A hinge 27 connects the coplanar segment 21 to the rear-beam 17 (col. 3, lines 1-8). As compared to the position of the blade edges relative to the guard bar at the normal or free position set in accordance with a predetermined blade geometry (FIG. 3), a change in blade geometry occurs during the course of shaving when a shaving force F causes the blade package to rotate or pivot about rear-beam 17 in the direction of arrow R where the blade edges are rendered less "aggressive" (FIG. 4, col. 3, lines 13-23). Upon relaxation of shaving forces, the elastic memory of hinges 24,26,27,28 forces the blade seat, and therefore the blade edges, to return to their normal position (FIG. 3., col. 3, lines 24-26).
In an alternative embodiment, Ciaffone et al. shows the blade seat is hinged to a front beam 175 by webs 240,260,270,280 (FIGS. 6-10, col. 3, lines 46-48). Upon exertion of a shaving force F' (FIG. 9) onto the cap 330, the coplanar segments 180,190,210 and 220, move in the direction of the arrow R (FIG. 9) to provide a more aggressive edge exposure (col. 4, lines 1-9). As in the embodiment of FIGS. 1-5, the elastic memory of the hinges 240,260,270,280 forces the blade edges to return to the free position when shaving forces are released (col. 4, lines 11-13).
Oldroyd et al., U.S. Pat. No. 4,063,354, discloses a shaving unit wherein a blade unit comprises two blades separated by a spacer 5 (FIGS. 13-16). A resiliently flexible metallic or plastic guard 3 is secured to the blade unit by spot welding or other means (col. 3, lines 26-28). The blade unit, which is illustrated in its normal forward position of maximum blade exposure in FIG. 13, can bow rearwardly under pressure applied during shaving to carry the blade unit along a plane to the rear, relative to the platform 1 and cap 4. This reduces blade exposure but increases the shaving angle, as indicated by dotted lines 3' in FIGS. 13 and 15 (col. 3, lines 26-37).
Althauset et al., U.S. Pat. No. 5,074,042, discloses a shaver head comprising two staggered blades 7 embedded in a blade block 6 (FIG. 3). A cover cap portion 9 covers the top side of the blade block 6 (col. 3, lines 12-15). A spring 14 is placed between the blade block 6 and a body 2. The blade block 6, together with the two staggered blades 7, can swivel about an axis A (col. 3, lines 17-43). During shaving, pressure is applied to the razor blade unit, thereby causing the blade block 6 to swivel and alter shaving geometry of the blades (col. 3, lines 46-60).
Jacobson U.S. Pat. Nos. 4,442,598, 4,378,634 and 4,270,268 disclose a razor blade assembly including a body member 2 having blade means 36,36' being independently movable in response to spring finger biasing means 18,18' integral with the body member. In the Jacobson patents, the spring fingers 18,18' move the blade means 36,36' along planes defined by slots 16 in end portions 4,6 of the body member 2.
None of the patents described above provides the important advantages of using the combination of front and rear double cantilevered springs to support a blade assembly within a body portion of a shaving cartridge or the like to precisely control blade geometry of exposure and shaving angle in response to shaving forces. None of the prior art patents use a four-bar linkage formed by the combination of rotatable front and rear double cantilever springs (or links) connected to a stationary and movable blade assembly to translate shaving forces encountered from any direction into predictable and precisely controlled blade movement to achieve the correct exposure and shave angle.